He was the eldest son of Prithvi Narayan Shah, the king who started the unification of Nepal.

Pratap Singh Shah ruled for only 36 months, up to 1777, and died of smallpox at the age of 26.

He was succeeded by his two-year-old son Rana Bahadur Shah.

He did not actively participate in the unification campaign led by his father.

The boundaries of Nepal continued to extend after his reign, as his wife Rajendra Laxmi and his brother Prince Bahadur Shah continued the unification campaign as regents of his son Ranabahadur Shah.